Adsorbed Tween 80 is unique in its ability to improve the stability of gold nanoparticles in solutions of biomolecules.

This report shows that, of the Tween series (Tween 20, Tween 40, Tween 60 and Tween 80) of nonionic surfactants adsorbed on gold nanoparticles (NPs), Tween 80 makes the NPs most stably dispersed in aqueous solutions with or without the presence of representative biological molecules, such as nucleic acids or proteins of different sizes, isoelectric points (pIs) and shapes. In addition, the stability of gold NPs already modified with poly(L-lysine)-graft-poly(ethylene glycol) (PLL-PEG) or hexa(ethylene glycol)-terminated undecanylthiol (HS(CH(2))(11)EG(6)OH) is further improved in solutions of proteins when Tween 80 is co-adsorbed on the gold NPs. This strategy is the most effective when adsorption of Tween 80 on gold NPs precedes the coating of PLL-PEG or HS(CH(2))(11)EG(6)OH on the NPs.